Oral/nasal cannula manifold

ABSTRACT

An oral/nasal cannula manifold gas sampling and oxygen delivering manifold for sampling exhaled breath of a subject and delivering supplemental oxygen, the cannula including a main body portion having a suction port which is connected with a collection tube to a suction device for sampling the exhaled breath of the subject. A nasal prong upwardly protrudes from the main body portion and is positioned for insertion into a nostril of the subject to collect nasally exhaled breath. An oral conduit passage is embedded in a deflector/concentrator plate that extends downwardly from the main body portion. The straight conduit passages of the nasal and oral passages are connected to and aligned in the same plane whereby the opposed nasal and oral conduit passages are connected with the conduit passage of the suction port without any adjacent connected void volumes or dead spaces in any of the passages.

FIELD OF THE INVENTION

The present invention relates to the field of oral/nasal cannulamanifold for use in sampling breath of subjects, especially for thepurpose of providing capnographic data concerning the subject.

BACKGROUND OF THE INVENTION

During anesthesia, and especially during sedation anesthesia or patientcontrolled analgesia it is often desirable to collect and analyzequalitatively and quantitatively the constituents of gases respired bythe patient.

Oral/nasal cannula manifolds are used to deliver supplemental oxygen tohospital patients who require respiratory support and to collect carbondioxide samples from the patients to monitor respiration. The oral/nasalmanifold is configured to be in close proximity to the oral cavity andalso inserted into the nasal cavity of the patient. The patient'sexhaled breath is drawn through the manifold passages to a gas analyzerto be analyzed. The results of this analysis provides an indication ofrespiratory adequacy.

The accuracy of this analysis of exhaled gases depends on the ability ofa sampling system to optimally move a gas sample from the patient to thegas analyzer while maintaining a smooth, laminar flow of gases, suchthat there are as few alterations to the waveform and response time ofthe concentration of the gases as possible. The waveform of theconcentration of the gas is critical for accurate analysis. As the gasmixtures travel from the patient to the gas analyzer, the concentrationof the gases can be effected by mixing of the component gases, whichreduces the accuracy of the analysis of the sample by the gas analyzer,and reduces the amount of information obtained from the analysis.

As is pointed out in U.S. Pat. No. 6,422,240, prior art oral/nasalcannulas have caused significant alterations to these important featuresof the internal structure of the stream of exhaled gases. For example,alterations arise as a result of attempt to combine the delivery ofoxygen with the sampling of the exhaled breath of the patient. Asanother example, prior art oral/nasal cannulas have cannula passageswhich include connected adjacent or ancillary void volumes (space whichis not part of the designated pathway for the flow of gases), and inaddition, the cannula passages have curved sections which providerestriction to flow of the respired gases and therefore providedifferent flow rates in connected cannula passages. Accordingly, thewaveform of the concentration of the gas is altered and accurateanalysis is not provided. There is accordingly a need to provide anoral/nasal manifold which provides optimal sampling of the subjectsexhaled gases for analysis in order to provide an optimal waveform fromthe analyzer.

The deficiency in these prior art designs is the undesirable diminishedfidelity resulting from gas sampling flow dynamics. Specifically, theamount of curvature in the cannula passages and the amount of dead orvoid space gases, which have limited or no carbon dioxide content, thatis analyzed along with the actual ventilatory gases, results in adiluted sample which produces a lesser quality or low fidelity signalgeneration.

In fact, the flow path created by the drafting effect in the cannulapassages is more prominent on the void or dead space gases. Thisfacilitates the production of diluted end title carbon dioxide data andprovides a lesser fidelity capnographic waveform and the curvatures andancillary void volumes in the cannula passages prevent optimalcancellation of signal degradation caused by lack of expiration at theopposite site. In other words, the nasal and oral samples are somewhatin parallel and not in opposition with each other thereby providingdegraded sampling quality.

SUMMARY OF THE INVENTION

The oral/nasal manifold of the present invention is provided forsampling exhaled breath of a patient and to thereby provide an optimalsampling of the subject's exhaled gases for analysis. The oral/nasalmanifold is provided with a main body portion having formed therein asuction port which is dimensioned and adapted to be connected with acollection conduit to a suction device for capnographic analysis. Anasal prong protrudes from the main body portion and is positioned forinsertion into a nostril of the subject to collect nasally exhaledbreath of the subject. The nasal prong is provided with a straightcannula passage in fluid flow communication with a conduit passage ofthe suction port. An imbedded oral conduit also passes through the mainbody portion in an opposite direction and is provided also with astraight passage with a distal opening positioned for placement near theoral cavity or mouth of the subject to collect orally exhaled breath ofthe subject. This oral conduit passage is also in fluid flowcommunication with the conduit passage of the suction port.

The straight manifold passage of the nasal prong is connected to andaligned in the same plane as the straight conduit passage of the oralsampling port whereby the opposed nasal and oral passages are connectedwith the conduit passage of the suction port without any adjacentconnected dead or void volumes and without any curvatures in therespective passages. Accordingly, the pressure of the exhaled nasal andoral gases of the subject directly oppose each other in the straightaligned passages to provide optimal sampling of the subject's exhaledgases for analysis. This opposing effect provides cancellation of theinfluences of the oral and nasal sites, one against the other, withoutthe inclusion of flow restrictions due to cannula passage curvature andwithout the influence of adjacent or ancillary included void volumes ordead spaces in the manifold passages.

To ensure effective analysis, the following features also improveaccuracy in the oral/nasal sampling manifold of the present invention.The passage of the suction port is connected at a right angle to thestraight aligned nasal and oral conduit passages and is connectedcentrally between their distal ends. The internal volumes of the opposedaligned passages are preferably equal, as well as the internal diametersthereof. The opposed passages are also preferably equal in length.

In order to enhance performance of the oral collection portal, adeflector concentrator plate is provided whereby it surrounds the distalopening of the oral conduit prong. This provides an significantlygreater surface area from which to obtain a more accurate representativecarbon dioxide sample from the oral collection portal.

It is further preferable that the main body portion and the collectionpathway of the oral/nasal manifold be formed of a flame retardantthermoplastic polymer in order to reduce the hazzard of fire sometimesexperienced with the use of supplemental oxygen administration.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages appear hereinafter in the followingdescription and claims. The accompanying drawings show, for the purposeof exemplification, without limiting the scope of the invention orappended claims, certain practical embodiments of the present inventionwherein:

FIG. 1 is a front view of the oral/nasal gas collection manifold of thepresent invention;

FIG. 2 is a back view of the oral/nasal gas collection manifold shown inFIG. 1;

FIG. 3 is a perspective front view of the oral/nasal gas collectionmanifold shown in FIG. 1;

FIG. 4 is a perspective back view of the oral/nasal gas collectionmanifold of FIG. 1;

FIG. 5 is a top view of the oral/nasal gas collection manifold shown inFIG. 1;

FIG. 6 is a bottom view of the oral/nasal gas collection manifold shownin FIG. 1; and

FIG. 7 is a left side view of the oral/nasal gas collection manifoldshown in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings, oral/nasal cannula manifold 10 of the presentinvention is provided for sampling exhaled breath of a subject andincludes a main body portion 11 having formed therein a suction port 12(FIG. 1) which is dimensioned and adapted to be connected with acollection tube (not shown) to a suction device (not shown) for samplingof exhaled breath of the subject known as a capnographic analyzer in theindustry for determining the respired CO₂ content.

A nasal prong 13 protrudes upwardly from main body portion 11 and ispositioned for insertion into a nostril (similar to that as shown at 14in FIG. 7) to collect nasally exhaled breath of the subject 15. Nasalprong 13 is provided with an internal straight passage 16 which is influid flow communication with conduit passage 17 of suction port 12.

Oral prong 18 is directed downwardly through the main body portion 11and is also provided with a straight conduit passage 19 having a distalopening 20 for placement near the mouth or oral cavity 21 (FIG. 7) ofsubject 15 to collect orally exhaled breath of subject 15. This conduitpassage 19 is also in fluid flow communication with the cannula passage17 of suction port 12.

The straight conduit passage 16 of nasal prong 13 is connected to andaligned in the same plane as the straight conduit passage 19 of oralprong 18 whereby the opposed nasal and oral passages 16 and 19 areconnected with conduit passage 17 of suction port 12 without anyadjacent connected void volumes or dead spaces in any of theserespective passages. In view of this, the pressure of the exhaled nasaland oral gases of subject 15 directly oppose each other in the straightaligned conduit passages 16 and 19 to thereby provide optimal samplingof the subject's exhaled gases for analysis.

To enhance this feature of optimal sampling, the conduit passage 17 ofsuction port 12 is preferably connected at a right angle as shown inFIG. 1 to the straight aligned conduit passages 16 and 19, and isconnected centrally between their distal ends. Preferably also theinternal volumes of the opposed aligned conduit passages 16 and 19 areequal and the internal diameters of these opposed aligned conduitpassages are also equal. To preferably also enhance this feature, theopposed conduit passages 16 and 19 are also equal in length. Thisprovides for effective reciprocal cancellation at the site of lessexpiratory force.

Main body portion 11 also includes a curved deflector/concentrator plate22 which surrounds the distal opening 20 of oral prong 18 in order todeflect and concentrate orally exhaled breath from the subject andthereby provide a heavier concentration of the exhaled breath withlimited dilution.

Main body portion 11, including all integral collection conduit elementsthereof, is preferably manufactured of a flame retardant thermoplasticpolymer in order to provide an oral/nasal gas collection/deliverymanifold which will not propagate or support combustion even in thepresence of increased concentrations of oxygen, thereby limitingpossible hazardous injuries to the subject.

As viewed in FIG. 1, the left side of the body portion 11 is providedwith an oxygen delivery prong 23 which is provided therein with anoxygen delivery passage 24, which in turn is connected to thehorizontally oriented oxygen delivery passage 25. Oxygen deliverypassage 25 is in turn connected to oxygen supply port 26 which isdimensioned and adapted to receive the terminal end of a flexible oxygensupply tube for supplying oxygen under pressure from a source (notshown).

Oxygen supply passage 25 also exits to oral oxygen supply port 27 whichsupplies a stream of oxygen directed downwardly over the surface of thedeflector/concentrator plate towards the mouth of the subject for oralinhalation. However, port 27 is positioned from the outer surface of thedeflector plate 22 as indicated in FIGS. 1 and 2, while distal port 20of passage 19 is situated on the underside of the plate 22 so that theoxygen supply ejected from port 27 does not interfere with or dilute theexpired CO₂ oral samples entering distal opening 20. In fact, it will berealized that all of the oxygen supply is removed as far as possibleaway from the exterior distal ports of nasal prong 13 and oral conduitpassage 19 so as to prevent any interference between the oxygen supplyand the expired or exhaled breath being sampled.

On the outer surface of deflector/concentrator plate 22, a series ofraised dispersion protrusions 28 act to create a more uniform envelopeof increased oxygen concentration about the mouth and nose.

Raised concentration protrusions 29 on the underside of plate 22 serveto localize a more representative concentration of orally expired carbondioxide for optimal gas analysis and interpretation.

I claim:
 1. An oral/nasal gas sampling and oxygen delivery manifold forsampling exhaled breath of a subject and delivering supplemental oxygen,comprising: a main body portion having formed therein a suction portwhich is dimensioned and adapted to be connected with a collection tubeto a suction device for sampling of exhaled breath of said subject; anasal prong protruding from said main body portion and positioned forinsertion into a nostril of said subject to collect nasally exhaledbreath of said subject, and having a straight passage in fluid flowcommunication with a conduit passage of said suction port; and an oralprong protruding from said main body portion and having a straightconduit passage with a distal opening positioned for placement near anoral cavity of said subject to collect orally exhaled breath of saidsubject, and in fluid flow communication with the conduit passage ofsaid suction port; the straight passage of said nasal prong connected toand aligned in the same plane as the straight conduit passage of saidoral prong whereby the opposed nasal and oral passages are connectedwith said conduit passage of said suction port without any adjacentconnected void volumes in any of said passages, and the pressure of theexhaled nasal and oral gases of said subject directly oppose each otherin said straight aligned passages to provide optimal sampling of thesaid subjects exhaled gases for analysis.
 2. The oral/nasal manifold ofclaim 1, wherein the conduit passage of said suction port connects at aright angle to said straight aligned passages and centrally betweentheir distal ends.
 3. The oral/nasal manifold of claim 2, wherein theinternal volumes of said opposed aligned conduit passages are equal. 4.The oral/nasal manifold of claim 3, wherein the internal diameters ofsaid opposed aligned conduit passages are equal.
 5. The oral/nasalmanifold of claim 4, wherein said opposed conduit passages are equal inlength.
 6. The oral/nasal manifold of claim 1, said main body portionincluding a deflector/concentrator plate surrounding said distal openingof said oral conduit passage, said oral conduit passage imbedded in saidplate.
 7. The oral/nasal manifold of claim 1, wherein said main bodyportion and said prongs are comprised of a flame retardant thermoplasticpolymer.
 8. An oral/nasal manifold for collection of exhaled nasal andoral gases respired by a patient, comprising: two nasal prongs forinsertion into nostrils of the patient; a collection tube for thecollection of exhaled gases from the patient, one end of said tubeconnected to one of said nasal prongs; and an oral conduit prong forplacement near an oral cavity of the patient for the collection oforally exhaled gases from the patient, the conduit passage of said onenasal prong passage and said oral conduit passage being straight, andthe straight passage of said oral conduit connected to and aligned inthe same plane as the straight passage of said one of said nasal prongs,whereby the aligned conduit passages are connected with the conduitpassage of said collection tube without any adjacent connected voidvolumes in any of said cannula passages, and the pressures of theexhaled nasal and oral gases of the patient directly oppose each otherin said straight aligned passages to provide an optimal sampling of thepatient's exhaled gases for analysis.
 9. The oral/nasal manifold ofclaim 8, wherein the conduit passage of said collection tube connects ata right angle to said straight aligned conduit passages and centrallybetween their distal ends.
 10. The oral/nasal manifold of claim 9,wherein the internal volumes of said opposed and aligned conduitpassages are equal.
 11. The oral/nasal manifold of claim 10, wherein theinternal diameters of said opposed and aligned conduit passages areequal.
 12. The oral/nasal manifold of claim 11, wherein said opposed andaligned conduit passages are equal in length.
 13. The oral/nasalmanifold of claim 8, including a deflector/concentrator platesurrounding a distal opening for said oral conduit passage.
 14. Theoral/nasal manifold of claim 8, wherein said main body portion and saidprongs are constructed of a flame retardant thermoplastic polymer.
 15. Amethod of collecting exhaled gases from a patient, the methodcomprising: providing an oral/nasal manifold having two nasal prongs forinsertion into the nostrils of the patient with one end of a collectiontube for collecting exhaled gases from the patient connected to theconduit passage of one of the nasal cannula prongs, and an oral prongwith a distal port for placement near the oral cavity of the patient andhaving a straight conduit passage connected with a straight conduitpassage of said one of the nasal prongs; connecting the straight conduitpassage of said oral prong to said straight conduit passage of said onenasal prong in alignment in the same plane and thereby providing aconnection to the conduit passage of said collection tube without theinclusion of any ancillary void volumes in any of said conduit passages;inserting said nasal prongs into the nostrils of the patient; placingsaid oral distal port near the oral cavity of the patient; attachingsaid collection tube to a gas analyzer; and applying a vacuum force atsaid gas analyzer, such that the exhaled gases flowing through theconnected manifold conduit passages move from said collection tube tosaid gas analyzer and the pressures of the exhaled nasal and oral gasesof the patient directly oppose each other in said straight alignedconduit passages to provide an optimal sampling of the patient's exhaledgases for analysis.
 16. The method of claim 15, including connectingsaid one end of said collection tube to said aligned passages wherebythe conduit passage of said collection tube is connected thereto at aright angle.
 17. The method of claim 16, including providing saidopposed aligned passages with equal internal volume.
 18. The method ofclaim 17, including providing said opposed aligned passages with equalinternal diameters.
 19. The method of claim 15, including constructingsaid oral/nasal manifold of a flame retardant thermoplastic polymer. 20.The method of claim 15, including concentrating orally exhaled breathfrom the patient about the distal port for said oral prong.